In this resubmission application for a K23 Mentored Patient Oriented Research Career Development Award, Dr. Christina Brezing proposes a comprehensive plan for developing into an independent researcher capable of investigating and, ultimately, customizing pharmacologic treatments for individuals with cannabis used disorder (CUD) with the aid of technology to improve our assessments and treatment outcomes. CUD is a chronic relapsing-remitting illness that impacts millions of adults in the United States. While there have been a number of randomized controlled trials of medication treatments for CUD, none have emerged as clearly efficacious. Impulsivity has been identified as both a predictor and consequence of CUD yet medication treatment trials have not clearly targeted this. Dr. Brezing's proposal aims to determine the effectiveness of lorcaserin, a serotonin 2c receptor agonist, in reducing cannabis use and decreasing dissociable constructs of impulsivity as measured by behavioral tasks and self-report at study visits and through ecological momentary assessments (EMA). We hypothesize that the lorcaserin group will have greater reductions in cannabis use and decreased impulsivity across measures as compared to placebo. The project will add to important and growing literature on the role of impulsivity in CUD and treatment in addition to providing a strategy for harnessing technology to make in vivo assessments during trials. Finally, this project serves as a mechanism to gather data that will lay the groundwork for future largerclinical trials and implementation efforts for technology in this context. While pursuing this line of research with the expertise of her mentors (Drs. Frances Levin and Edward Nunes) and collaborators (Dr. Valerie Voon andDr. Martina Pavlicova), Dr. Brezing will concurrently engage in an individualized training program so as to develop in the following important areas: (1) clinical research methodology (2) biostatistics for clinical trials (3) neurobiology and behavioral assessments of impulsivity (4) applications of technology to the treatment of substance use disorders, and (5) grant writing and management. This training program will build upon Dr. Brezing's background as a board certified addiction psychiatrist who has a growing expertise in substance use disorder treatment trials, but who has relatively little experience in fully assessing dissociable components of impulsivity and applications of technology. The K23 award will support an innovative and clinically relevant program of patient-oriented research, while helping Dr. Brezing acquire critical skills that will ensure her development into an independent clinical researcher poised to impact the field of cannabis and other substance use disorder treatment.